Retinal horizontal cells

Studies on teleost fish and mammals have demonstrated the existence of non-rod, non-cone ocular photoreceptors. In the case of VA opsin in the roach, electrophysiological evidence suggests that one function of this photosensory photopigment is to modulate the activity of retinal horizontal cells. To what end remains unclear, but this fits with the general role of horizontal cells in the teleost... 

Kojima D, Mano H, Fukada Y 2000 Vertebrate ancient-long opsin a green-sensitive photoreceptive molecule present in zebrafish deep brain and retinal horizontal cells. J Neurosci 20 2845-2851... 

Figure 30-10 (A) Schematic drawing of a synapse. (B) Electron micrograph showing the synaptic junctions in the basal part (pedicle) of a retinal cone cell of a monkey.403 Each pedicle contains synaptic contacts with 12 triads, each made up of processes from a bipolar cell center that carries the principal output signal and processes from two horizontal cells that also synapse with other cones. A ribbon structure within the pedicle is characteristic of these synapses. Note the numerous synaptic vesicles in the pedicle, some arranged around the ribbon, the synaptic clefts, and the characteristic thickening of the membranes surrounding the cleft (below the ribbons). Micrograph courtesy of John Dowling.

Figure 2.2 The retina consists of three layers. Retinal ganglion cells are located at the top followed by a layer of bipolar cells and receptors at the bottom. Light has to pass through the top two layers to reach the light-sensitive sensors. Information then travels upward from the receptors to the bipolar cells and on to the retinal ganglion cells. Information is also exchanged laterally through amacrine and horizontal cells. (Retina illustration from LifeART Collection Images 1989-2001 by Lippincott Williams Wilkins, used by permission from SmartDraw.com.

Rodrigues Pdos S, Dowling JE (1990) Dopamine induces neurite retraction in retinal horizontal cells via diacylglycerol and protein kinase C. Proc Natl Acad Sci USA 87 9693-9697. 

Based on results in vertebrates Bodis-Wollner (1990) assumed that in primates the surround organization of the retinal ganglion cell is under D1 receptor control. D1 receptor activation causes disjunction of horizontal cells, otherwise coupled in... 

Figure I. Structure of a ciliated photoreceptor cell in vertebrates. (A) Scheme of a rod photoreceptor cell. (B) Transmission electronmicroscopy image of a part of a mouse rod photoreceptor cell. The apical extensions of cells of the retinal pigment epithelium (RPE) evolve the tips of photoreceptors light-sensitive outer segments (OS). The OS is linked via a connecting cilium (CC) to an inner segment (IS) which bears the basal body complex (BB) in its apical region. Synaptic terminals (S) link the photoreceptor cell and the 2nd-order neurons, bipolar and horizontal cells. N = nucleus in B, arrow point to axonemal microtubules projecting into the OS. Bar in B = 0.2 p,m...

Keywords Amacrine cell Bipolar cell Cone Fovea Horizontal cell Muller cells Photoreceptor Retina Retinal ganglion cell Rod... 

Figure 11.2. The five major retinal cell types (photoreceptors, bipolai cells, horizontal cells, amacrine cells, and ganglion cells) and tlieir synaptic connections.

The GABA receptor is insensitive to allosteric modulators, such as benzodiazepines and barbiturates. Native responses of the GABA receptor type occur in retinal bipolar or horizontal cells across vertebrate species. Although the term GABA receptors is still being used frequently they have been reassigned as part of GABA receptor family. 

Twig G, Levy H, Perlman I (2003) Color opponency in horizontal cells of the vertebrate retina. Prog Retin Eye Res 22 31-68. 

Retinal horizontal cells The model of Winslow and Knapp [1991] consisted of a fast sodium current, an inactivating (A-type) potassium current, a noninactivating potssium current, an anomalous rectifier potassium current, a calcium-inactivated calcium current, and a linear leakage current. In addition calcium concentration changes in a restricted region beneath the membrane was also modeled. 

Winslow, R.L. and A.G. Knapp (1991). Dynamic models of the retinal horizontal cell network. Prog. Biophys. Mol. Biol. 56,107-133. 

Resting potential, in membrane model, 22-2-22-3 Reswick, J., VII-2 Reticular lamina, 5-5 Retina, 4-2-4-3 Retinal ganglion cells, 22-12 Retinal horizontal cells, 22-12 Retinal stimulation, 35-2 Retinitis pigmentosa, sec RP Reul, H 44-3,55-5,55 12 Reynolds, D.V., 29-10 Rho,J.Y.,47-9 Rhode, W.S., 5-4,63-9 Rhythmic electrical activity, in gastrointestinal system, 6-6... 

Fig. 5 Retinal interconnection of rods and cones via rod bipoiars (RB), ON and OFF cone bipolars (CB), horizontal cells (H, HI), and amacrine cells (All, A) to ganglion cells (GC). Small dots indicate inhibitory, large dots excitatoty connections. The horizontal interconnections as well as the connection of ON and OFF cells with cones show the formation of differential signals, whereas the rod signal is mainly superimposed onto the feed of the optical nerve...

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